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Article: DFT study on the mechanism of amides to aldehydes using Cp 2Zr(H)Cl

TitleDFT study on the mechanism of amides to aldehydes using Cp 2Zr(H)Cl
Authors
Issue Date2010
PublisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/organometallics
Citation
Organometallics, 2010, v. 29 n. 1, p. 42-51 How to Cite?
AbstractDensity functional theory (DFT) calculations at the B3LYP/6-31G(d,p) (LANL2DZ for Zr) level of theory were performed to elucidate the reaction mechanism for the reduction of amides to aldehydes using Cp 2Zr(H)Cl as a reducer. In particular, a detailed study was done that involved a proposed iminium cation species in the reaction mechanism. Our calculations suggest the first step of the reaction is the insertion of the C=O moiety into Zr-H through an "inside" mode of action that leads to the formation of a Zr-O intermediate that has been observed in previously reported experiments. Under anhydrous conditions, the cleavage of the O-C bond of the Zr-O intermediate results in the formation of an iminium cation, but this process is both kinetically and thermodynamically unfavorable. Nevertheless, under hydrous conditions, the cleavage of the O-C bond of the Zr-O intermediate leads to the formation of a highly active iminium cation intermediate, and this process occurs with the assistance of water hydrogen bonding. This step is also the rate-determining step, and the activation energy was determined to be 19.8 kcal/mol. Subsequently a water molecule attacks the iminium cation to produce an amine intermediate. Finally, the water-catalyzed elimination reaction occurs to yield the aldehyde product. Water hydrogen bonding plays an important role in assisting the cleavage of the O-C and the C-N bonds during the reaction. The above reaction mechanism indicates that the sources of the aldehyde-group oxygen and the hydrogen in the aldehyde product are H 2O and Cp 2Zr(H)Cl, respectively, which is consistent with the experimental observations of Georg and co-workers. © 2009 American Chemical Society.
Persistent Identifierhttp://hdl.handle.net/10722/168425
ISSN
2015 Impact Factor: 4.186
2015 SCImago Journal Rankings: 2.043
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorWang, Jen_US
dc.contributor.authorXu, Hen_US
dc.contributor.authorGao, Hen_US
dc.contributor.authorSu, CYen_US
dc.contributor.authorZhao, Cen_US
dc.contributor.authorPhillips, DLen_US
dc.date.accessioned2012-10-08T03:18:47Z-
dc.date.available2012-10-08T03:18:47Z-
dc.date.issued2010en_US
dc.identifier.citationOrganometallics, 2010, v. 29 n. 1, p. 42-51en_US
dc.identifier.issn0276-7333en_US
dc.identifier.urihttp://hdl.handle.net/10722/168425-
dc.description.abstractDensity functional theory (DFT) calculations at the B3LYP/6-31G(d,p) (LANL2DZ for Zr) level of theory were performed to elucidate the reaction mechanism for the reduction of amides to aldehydes using Cp 2Zr(H)Cl as a reducer. In particular, a detailed study was done that involved a proposed iminium cation species in the reaction mechanism. Our calculations suggest the first step of the reaction is the insertion of the C=O moiety into Zr-H through an "inside" mode of action that leads to the formation of a Zr-O intermediate that has been observed in previously reported experiments. Under anhydrous conditions, the cleavage of the O-C bond of the Zr-O intermediate results in the formation of an iminium cation, but this process is both kinetically and thermodynamically unfavorable. Nevertheless, under hydrous conditions, the cleavage of the O-C bond of the Zr-O intermediate leads to the formation of a highly active iminium cation intermediate, and this process occurs with the assistance of water hydrogen bonding. This step is also the rate-determining step, and the activation energy was determined to be 19.8 kcal/mol. Subsequently a water molecule attacks the iminium cation to produce an amine intermediate. Finally, the water-catalyzed elimination reaction occurs to yield the aldehyde product. Water hydrogen bonding plays an important role in assisting the cleavage of the O-C and the C-N bonds during the reaction. The above reaction mechanism indicates that the sources of the aldehyde-group oxygen and the hydrogen in the aldehyde product are H 2O and Cp 2Zr(H)Cl, respectively, which is consistent with the experimental observations of Georg and co-workers. © 2009 American Chemical Society.en_US
dc.languageengen_US
dc.publisherAmerican Chemical Society. The Journal's web site is located at http://pubs.acs.org/organometallicsen_US
dc.relation.ispartofOrganometallicsen_US
dc.titleDFT study on the mechanism of amides to aldehydes using Cp 2Zr(H)Clen_US
dc.typeArticleen_US
dc.identifier.emailPhillips, DL:phillips@hku.hken_US
dc.identifier.authorityPhillips, DL=rp00770en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.doi10.1021/om900371uen_US
dc.identifier.scopuseid_2-s2.0-73649142370en_US
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-73649142370&selection=ref&src=s&origin=recordpageen_US
dc.identifier.volume29en_US
dc.identifier.issue1en_US
dc.identifier.spage42en_US
dc.identifier.epage51en_US
dc.identifier.isiWOS:000273263500008-
dc.publisher.placeUnited Statesen_US
dc.identifier.scopusauthoridWang, J=7701308647en_US
dc.identifier.scopusauthoridXu, H=35328606500en_US
dc.identifier.scopusauthoridGao, H=36666205500en_US
dc.identifier.scopusauthoridSu, CY=7402820091en_US
dc.identifier.scopusauthoridZhao, C=7403563836en_US
dc.identifier.scopusauthoridPhillips, DL=7404519365en_US
dc.identifier.citeulike6488775-

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